title: Comparing a new ultrasound approach with electrodiagnostic studies to confirm clinically defined carpal tunnel syndrome: a prospective, blinded study.
abstract: OBJECTIVE
  The aims of this study were to compare electrodiagnostic (EDX) confirmation of clinical diagnosis of carpal tunnel syndrome (CTS) with ultrasonography (US), using a new set of normal values taking wrist circumference of subjects into account, and to determine whether EDX examination can be replaced by US to confirm CTS.
  
  
  METHODS
  A prospective cohort of 156 patients with idiopathic CTS underwent US and EDX studies. Upper levels of normal cross-sectional area of the median nerve were established by taking wrist circumference into account and using linear regression equations.
  
  
  RESULTS
  Of the selected patients, 83.3% met the EDX criteria for CTS. The findings from the US were normal in 67 (42.9%) of 156 patients, and within this group, the findings from the EDX were abnormal in 44 patients (65.7%). Of 89 patients with abnormal findings from the US, only 3 patients had normal findings from the EDX.
  
  
  CONCLUSIONS
  US cannot replace EDX for confirmation of clinical diagnosis of CTS. However, an abnormal US test result has a high positive predictive value for abnormal EDX result in clinically defined CTS. US might reveal relevant anatomic information preoperatively that rarely has a direct influence on treatment management of patients with CTS. US testing, taking morphometric data into account, does not have the same diagnostic value as EDX does in confirming CTS.
authors.affiliation: From the Department of Neurology and Clinical Neurophysiology, Canisius Wilhelmina Hospital, Nijmegen, the Netherlands (FC, KMK, JM, WIMV); Department of Neurology, Vlietland Hospital, Schiedam, the Netherlands (FC); and Department of Neurology and Clinical Neurophysiology, St Lucas Andreas Hospital, Amsterdam, the Netherlands (KMK).
authors.forename: Franka
authors.initials: F
authors.lastname: Claes
authors.forename: Kristel M
authors.initials: KM
authors.lastname: Kasius
authors.forename: Jan
authors.initials: J
authors.lastname: Meulstee
authors.forename: Wim I M
authors.initials: WI
authors.lastname: Verhagen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002349:Carpal Tunnel Syndrome / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D004568:Electrodiagnosis; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000000981:diagnostic imaging / Q000503:physiopathology; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D016037:Single-Blind Method; D014463:Ultrasonography; D055815:Young Adult